What were the alliance systems before World War 1 and why did they matter?
Before World War 1, Europe was divided into two major alliance systems: the Triple Alliance (Germany, Austria-Hungary, and Italy) and the Triple Entente (France, Russia, and Britain). These alliances meant that a conflict between two countries could quickly drag in all of Europe.
Steps
In 1882, Germany, Austria-Hungary, and Italy formed the Triple Alliance. They agreed to support each other if any of them was attacked by another major power.
In response, France and Russia formed their own alliance in 1894. Britain joined them in a series of agreements called the Entente Cordiale (1904, with France) and the Anglo-Russian Convention (1907), forming the Triple Entente.
These alliances were meant to keep the peace through a balance of power — the idea that no country would start a war if it meant fighting a whole group of nations.
Instead, the alliances had the opposite effect. When Austria-Hungary declared war on Serbia in 1914, Russia mobilized to help Serbia. Germany then declared war on Russia to support Austria-Hungary, which pulled France and Britain in on the other side.
Italy actually switched sides in 1915, joining the Entente after being promised territory. This shows that alliances were driven as much by self-interest as by loyalty.
Worked example
Think of the alliance system like a web of dominoes: Austria-Hungary declares war on Serbia (domino 1). Russia steps in for Serbia (domino 2). Germany backs Austria-Hungary and declares war on Russia (domino 3). France is allied with Russia and enters the war (domino 4). Germany invades Belgium to attack France, pulling Britain in (domino 5). Within a week, nearly all of Europe was at war.
Remember
The WW1 alliance system turned a regional conflict between Austria-Hungary and Serbia into a massive world war because each country's allies were obligated to join the fight.